1. Field of the Invention
The present invention relates to an air conditioner which contains therein a dust collecting device having a high voltage unit coupled to a power supply and discharge and dust collecting electrodes each coupled to the high voltage unit, and which has an air cleaning function for collecting by means of the dust collecting device dust contained in external air sucked by the rotation of a fan thereby to exhaust the air thus cleaned to the outside.
2. Description of the Related Art
Recently, the demand for keeping the air within a room to be clean to maintain comfortable live space has been increasing. In order to satisfy such a demand, an air cleaner or an air conditioner having an air cleaning function has been provided.
Further, as an apparatus for realizing such an air cleaning function, conventionally there has been provided an electronic dust collecting device including a discharge electrode and a dust collecting electrode. This dust collecting device is so arranged that a high voltage is applied between the discharge electrode and the dust collecting electrode to ionize dust within the peripheral air by means of the discharge electrode, thereby to adsorb (adhere) the ionized dust to the dust collecting electrode.
However, according to the air conditioner having such a dust collecting device, the dust collecting effect thereof degrades abruptly when an amount of dust adhered to the dust collecting electrode exceeds a predetermined value. The corona discharge may occur from the tip portion of the dust adhered to the dust collecting electrode depending on the situation thereby to generate smoke and stench. In order to prevent such a phenomenon, it is required to periodically remove the dust adhered to the dust collecting electrode.
However, when the air conditioner having the air cleaning function is so arranged that the dust collecting device is attached to the rear side of a heat exchanger, a user can not clean the dust collecting device. Thus, such an air conditioner requires a system (maintenance free system) for automatically cleaning the dust collecting device contained therein.
In view of the aforesaid matter, the inventors of the present invention have proposed an air conditioner arranged in a manner that, as a system for automatically cleaning the dust collecting device, a heating section (sheath heater or the like) is provided at the dust collecting electrode so that dust adhered to the dust collecting electrode is removed by heating the heating section (that is, dust is resolved into carbon dioxide (CO.sub.2) and water (H.sub.2 O) through the reaction with the catalyst of ceramics fused on the surface of the dust collecting electrode).
Such an air conditioner is required, at the time of executing the dust removing mode for removing the dust adhered to the dust collecting electrode by heating the heating section, to gradually resolve the dust while maintaining the resolving speed constant so as not to generate smoke and stench or the like when resolving the dust adhered to the dust collecting electrode. In order to satisfy such a requirement, it is required to strictly manage the surface temperature of the dust collecting electrode through the heating of the heating section. That is, the dust collecting electrode is required to be heated so that the surface temperature thereof increases gradually from the room temperature (about 20.degree. C.) to about 300.degree. C. along the temperature characteristic curve shown in FIG. 5.
In this manner, it is required to strictly manage the surface temperature of the dust collecting electrode in the dust removing mode so as not to generate smoke and stench due to the resolving of the dust.
However, if the dust removing mode is executed in parallel to the operation of the air conditioning function (that is, various kinds of operations such as a heating operation, a cooling operation, a dehumidifying operation, a blowing operation and the like), the surface temperature of the dust collecting electrode must be managed in a state where a fan rotates. Thus, there arises a problem that it is difficult to strictly manage the surface temperature of the dust collecting electrode so as to exhibit the temperature characteristic curve shown in FIG. 5. This is because the surface temperature of the dust collecting electrode is influenced by the wind generated by the rotation of the fan.